Alternative transportation fuels have been represented as enablers to reduce toxic emissions in comparison to those generated by conventional fuels. At the same time, tighter emission standards and significant innovation in catalyst formulations and engine controls has led to dramatic improvements in the low emission performance and robustness of gasoline and diesel engine systems.
One approach to addressing the issue of emissions is the employment of fuel cells, particularly solid oxide fuel cells (xe2x80x9cSOFCxe2x80x9d), in an transportation vehicle. A fuel cell is an energy conversion device that converts chemical energy into electrical energy. The fuel cell generates electricity and heat by electrochemically combining a gaseous fuel, such as hydrogen, carbon monoxide, or a hydrocarbon, and an oxidant, such as air or oxygen, across an ion-conducting electrolyte. The fuel cell generally consists of two electrodes positioned on opposite sides of an electrolyte. The oxidant passes over the oxygen electrode (cathode) while the fuel passes over the fuel electrode (anode), generating electricity, water, and heat.
A SOFC is constructed of solid-state materials, utilizing an oxygen ion conductive oxide ceramic as the electrolyte. The electrochemical cell in a SOFC is comprised of an anode and a cathode with an electrolyte disposed therebetween.
Application and research efforts during the twentieth century regarding applications of SOFCs was generally concentrated in the stationary power generation industry. Because of those SOFC designs, the SOFC was not readily adaptable for use in a transportation vehicle. A transportation vehicle application imposes specific temperature, volume, and mass requirements, as well as real world factors, such as fuel infrastructure, government regulations, and cost. Several other types of fuel cell systems (i.e. Proton Exchange Membrane (PEM) fuel cells) have been adapted for use in transportation vehicles, but require on-board storage or generation of hydrogen, and complex water management systems for on-board fuel reforming and system hydration. The on-board storage and water management systems add cost and complexity to the overall system.
The drawbacks and disadvantages of the prior art are overcome by a fuel cell comprising a pressure regulator and a method for pressure regulation.
A method of using a pressure regulator in a fuel cell system is disclosed. The method comprises controlling a purge gas pressure of a purge gas disposed in an enclosure disposed around a fuel cell stack and a waste energy recovery assembly, by seating a pressure plunger in a seating portion of a pressure regulator, wherein the purge gas unseats the pressure plunger when the purge gas pressure exceeds a desired pressure. The method further comprises passing a sufficient amount of the purge gas past the seating portion to reduce the purge gas pressure to at least the desired pressure.
A fuel cell system having a pressure regulator is also disclosed. The fuel cell system comprises an enclosure. A waste energy recovery assembly, a fuel cell stack and a pressure regulator are disposed in the enclosure. The fuel cell stack is in fluid communication with the waste energy recovery assembly. A purge gas is in fluid communication with the enclosure. The pressure regulator is in fluid communication with the purge air and an area external to the enclosure via the waste energy recovery assembly.
The above described and other features are exemplified by the following figures and detailed description.